Hall-Effect Sensors (eBook)

Theory and Application

Edward Ramsden (Autor)

eBook Download: EPUB

2011 | 2. Auflage
272 Seiten
Elsevier Science (Verlag)
978-0-08-052374-3 (ISBN)

Infos

"Without sensors most electronic applications would not exist-sensors perform a vital function, namely providing an interface to the real world. Hall effect sensors, based on a magnetic phenomena, are one of the most commonly used sensing technologies today. In the 1970s it became possible to build Hall effect sensors on integrated circuits with onboard signal processing circuitry, vastly reducing the cost and enabling widespread practical use. One of the first major applications was in computer keyboards, replacing mechanical contacts. Hundreds of millions of these devices are now manufactured each year for use in a great variety of applications, including automobiles, computers, industrial control systems, cell phones, and many others.

The importance of these sensors, however, contrasts with the limited information available. Many recent advances in miniaturization, smart sensor configurations, and networkable sensor technology have led to design changes and a need for reliable information. Most of the technical information on Hall effect sensors is supplied by sensor manufacturers and is slanted toward a particular product line. System design and control engineers need an independent, readable source of practical design information and technical details that is not product- or manufacturer-specific and that shows how Hall effect sensors work, how to interface to them, and how to apply them in a variety of uses. This book covers:
.the physics behind Hall effect sensors
.Hall effect transducers
.transducer interfacing
.integrated Hall effect sensors and how to interface to them
.sensing techniques using Hall effect sensors
.application-specific sensor ICs
.relevant development and design tools

This second edition is expanded and updated to reflect the latest advances in Hall effect devices and applications!

Information about various sensor technologies is scarce, scattered and hard to locate. Most of it is either too theoretical for working engineers, or is manufacturer literature that can't be entirely trusted. Engineers and engineering managers need a comprehensive, up-to-date, and accurate reference to use when scoping out their designs incorporating Hall effect sensors.

* A comprehensive, up-to-date reference to use when crafting all kinds of designs with Hall effect sensors

*Replaces other information about sensors that is too theoretical, too biased toward one particular manufacturer, or too difficult to locate

*Highly respected and influential author in the burgeoning sensors community"

Inhalt

Front Cover 1
Hall-Effect Sensors: Theory and Applications 4
Copyright Page 5
Contents 6
Chapter 1. Hall-Effect Physics 16
1.1 A Quantitative Examination 18
1.2 Hall Effect in Metals 20
1.3 The Hall Effect in Semiconductors 22
1.4 A Silicon Hall-Effect Transducer 24
Chapter 2. Practical Transducers 26
2.1 Key Transducer Characteristics 26
2.2 Bulk Transducers 31
2.3 Thin-Film Transducers 32
2.4 Integrated Hall Transducers 35
2.5 Transducer Geometry 41
2.6 The Quad Cell 42
2.7 Variations on the Basic Hall-Effect Transducer 45
2.8 Examples of Hall Effect Transducers 48
Chapter 3. Transducer Interfacing 50
3.1 An Electrical Transducer Model 51
3.2 A Model for Computer Simulation 53
3.3 Voltage-Mode Biasing 56
3.4 Current-Mode Biasing 60
3.5 Amplifiers 63
3.6 Amplifier Circuits 66
3.7 Analog Temperature Compensation 69
3.8 Offset Adjustment 72
3.9 Dynamic Offset Cancellation Technique 73
Chapter 4. Integrated Sensors: Linear and Digital Devices 76
4.1 Linear Sensors 77
4.2 Linear Transfer Curve 80
4.3 Drift 81
4.4 Ratiometry 82
4.5 Output Characteristics 83
4.6 Bandwidth 84
4.7 Noise 86
4.8 Power Supply Requirements for Linear Sensors 86
4.9 Temperature Range 87
4.10 Field-Programmable Linear Sensors 87
4.11 Typical Linear Devices 89
4.12 Switches and Latches 90
4.13 Definition of Switch vs. Latch 92
4.14 Switchpoint Stability 93
4.15 Bipolar Switches 93
4.16 Power Supply Requirements for Digital Sensors 94
4.17 Output Drivers 95
4.18 Typical Digital Devices 96
Chapter 5. Interfacing to IntegratedHall-Effect Devices 98
5.1 Interface Issues—Linear Output Sensors 98
5.2 Offset and Gain Adjustment 99
5.3 Output Thresholding 101
5.4 Interfacing to Switches and Latches 103
5.5 The Pull-Up Resistor 103
5.6 Interfacing to Standard Logic Devices 105
5.7 Discrete Logic 106
5.8 Driving Loads 108
5.9 LED Interfaces 108
5.10 Incandescent Lamps 109
5.11 Relays, Solenoids, and Inductive Loads 111
5.12 Wiring-Reduction Schemes 113
5.13 Encoding and Serialization 113
5.14 Digital-to-Analog Encoding 114
5.15 Mini-Networks 117
5.16 Voltage Regulation and Power Management 119
Chapter 6. Proximity-Sensing Techniques 122
6.1 Head-On Sensing 122
6.2 Slide-By Sensing 124
6.3 Magnet Null-Point Sensing 125
6.4 Float-Level Sensing 129
6.5 Linear Position Sensing 131
6.6 Rotary Position Sensing 133
6.7 Vane Switches 137
6.8 Some Thoughts on Designing Proximity Sensors 141
Chapter 7. Current-Sensing Techniques 146
7.1 Resistive Current Sensing 146
7.2 Free-Space Current Sensing 148
7.3 Free-Space Current Sensors II 151
7.4 Toroidal Current Sensors 155
7.5 Analysis of Slotted Toroid 157
7.6 Toroid Material Selection and Issues 158
7.7 Increasing Sensitivity with Multiple Turns 159
7.8 An Example Current Sensor 160
7.9 A Digital Current Sensor 161
7.10 Integrated Current Sensors 162
7.11 Closed-Loop Current Sensors 163
Chapter 8. Speed and Timing Sensors 166
8.1 Competitive Technologies 166
8.2 Magnetic Targets 168
8.3 Vane Switches 170
8.4 Geartooth Sensing 172
8.5 Geartooth Sensor Architecture 173
8.6 Single-Point Sensing 174
8.7 Single-Point/Fixed-Threshold Schemes 176
8.8 Single-Point/Dynamic-Threshold Schemes 178
8.9 Differential Geartooth Sensors 182
8.10 Differential Fixed-Threshold 184
8.11 Differential Variable-Threshold 185
8.12 Comparison of Hall-Effect Speed Sensing Methods 186
8.13 Speed and Direction Sensing 186
8.14 How Fast Do Speed Sensors Go? 188
Chapter 9. Application-Specific Sensors 192
9.1 Micropower Switches 192
9.2 Two-Wire Switches 195
9.3 Power Devices 197
9.4 Power + Brains = Smart Motor Control 198
Chapter 10. Development Tools 202
10.1 Electronic Bench Equipment 202
10.2 Magnetic Instrumentation 205
10.3 Mechanical Tools 211
10.4 Magnetic Simulation Software 214
Appendix A. A Brief Introduction 218
A.1 Where Magnetic Fields Come From 218
A.2 Magnetic Materials 220
A.3 Some Permanent Magnet Materials 225
Appendix B. Supplier List 226
Appendix C. Glossary of Common Terms 234
Appendix D. References and Bibliography 244
About the Author 246
Index 248

Produkt-Details

• Erscheint lt. Verlag: 1.4.2011
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Geografie / Kartografie
• Themenwelt: Technik ► Elektrotechnik / Energietechnik
• ISBN-10: 0-08-052374-9 / 0080523749
• ISBN-13: 978-0-08-052374-3 / 9780080523743